The video looks to me to depict an outside-of-combat trick that in GURPS would probably amount to a perk. At most, it could be a showy technique on Boxing (Sport). As a GM, I'd probably allow it to give a +1 to an Intimidation roll.

In any event, I wouldn't think it would have any real combat application. That's why we don't see any videos of this happening in a real fight. I don't see any reason to change the combat rules to account for this trick.